The purpose of this project is to study the Sensory-Decision-Theory Method in determining sensory discriminability and response bias in experimental pain. The investigation of the parametric approach for the evaluation of pain response components, d' and beta (as proposed by Clark, 1971) has been completed. The result of this study has been reported at the Second World Congress on Pain 1978. Current work involves investigation of the nonparametric estimation of the indices of pain response components (Pollack 1964, Hodos 1971, McNicol 1972). The sampling behavior of these indices will be extensively studied.